The present invention relates to the vibrational testing art and, more particularly, to a resonant apparatus for subjecting a test specimen to vibrational forces.
There have heretofore been proposed a number of apparatuses for performing vibrational tests on manufactured items. One such apparatus incorporates a voice coil or other electrodynamic means for imparting vibrational forces directly to a test specimen. However, the electrodynamic structures of such devices are rather complex and require a large number of high technology components. They are thus expensive to manufacture and generally must be operated by a qualified engineer.
Another prior device consists of an electric motor driving a cam or an unbalanced weight arrangement for vibrating a specimen. However, the frequency of vibration produced by such devices is generally limited to approximately 60 hertz, and the acceleration imparted to a specimen is proportional to the speed of the motor. The vibrational forces produced thus vary significantly over the range of possible frequencies.
A further vibrational device comprises one or more air hammers impacting a plate to impart a series of impulses to a test specimen. However, this device is also quite expensive and produces an undesirably high level of noise. In addition, an operator of the device has very little control over the spectrum of vibrations produced.
Therefore, in many applications it is desirable to provide a relatively simple and inexpensive apparatus for subjecting a test specimen to preselected vibrational forces.